La differenza tra il numero di tamponi e il numero delle persone testate | Il Post
La strategia dei tamponi: criteri, ritardi, criticità in Italia e all’estero | Valigia Blu
In Italy “tamponi” (“swabs”) refers to “performed tests”: many patients are tested several times (even 5 times). (high confidence | DPC)
In particular, patients who are recovered from COVID-19 are tested at least 3 times: 1 positive and 2 negative. (high confidence | DPC)
It should be taken into account the fact that “guariti” (“recovered”) in the official data refers not only to those actually recovered (who tested negative twice), but to all those discharged from hospital. (high confidence | DPC, IP, IS24O)
The total number of performed tests includes negative test results. (high confidence | DPC)
The total number of performed tests includes those that are pending results. (low confidence | DPC, PM, RP, RL)
Figures reported by Italy include all tests conducted in all working laboratories of the country. (medium-high confidence | MTP27-02, MTP09-03, MTP03-04)
Yes, all Italian regions and laboratories submit testing data on the same basis (i.e. “performed tests”). (medium-high confidence | DPC)
The figures published at a given date attempt to include all tests conducted up to that date, but significant and variable delays are present: both from symptom onset to lab confirmation (\(\Delta T_{symptoms}\)) and from lab confirmation to official database update (\(\Delta T_{lab}\)). (medium-high confidence | ISS)
The median delay between the symptom onset and the date of diagnosis is
For example, in Lombardy \(\Delta T_{symptoms}= 7.3 \text{ days } (1,20)_{95\% \text{CI}}\) and \(\Delta T_{lab} = 3.6 \text{ days } (1,10)_{95\% \text{CI}}\). (high confidence | AXV)
There have been significant changes over time in the ministerial testing protocol. (high confidence | ISS, MTP27-02, MTP09-03, MTP03-04, AXV)
Not all Italian regions follow the ministerial protocol of the central government, therefore there is significant regional heterogeneity in testing practices. (high confidence | IP, IP, IP)
Up to 20-03 we could identify 3 classes of testing practices described by the following pseudocode: consider two patients \(A\) and \(B\) living in the same house in the region \(R \in \{X, Y, Z\}\) such that
If \(A\) and \(B\) live in \(X\):
If \(A\) and \(B\) live in \(Y\):
If \(A\) and \(B\) live in \(Z\):
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